Baker's yeast, Saccharomyces cerevisiae, is commonly used as a leavening agent in dough, resulting in a baked product having organoleptic qualities such as taste, aroma and texture far superior to those associated with chemically leavened dough products. Commercial dough manufacturers preferably use yeast as a leavening agent as naturally leavened products are desired by consumers. Because consumers prefer the "fresh-baked" characteristics of dough products, many dough manufacturers sell pre-proofed dough in both frozen and refrigerated forms. "Pre-proofed dough" refers to dough which has been subjected to increased temperatures allowing the leavening agent in the dough to generate carbon dioxide sufficient to raise the dough to a desired volume. Proofing the dough before distributing it to consumers eliminates the need for the consumers to carefully proof the dough for an extended period of time before baking it. Refrigerated doughs are particularly convenient as they require no thawing and therefore can be baked into the desired product more rapidly than frozen doughs. Refrigerated doughs have a disadvantage compared to frozen doughs, however, in that the use of yeast as a natural leavener has not yet been successful in refrigerated doughs which need to be stored for any extended periods of time.
Examples of refrigerated dough compositions are described in Yong et at., U.S. Pat. Nos. 4,381,315 and 4,383,336; and Atwell, U.S. Pat. No. 4,526,801. Refrigerated doughs are prepared by combining the dough ingredients including a leavening agent, optionally placing the dough in containers, proofing the dough, and then storing the dough at refrigeration temperatures, i.e. between about 0.degree. C. and about 12.degree. C.
Refrigerated doughs are most commonly packaged prior to storage and may be packed prior to proofing the dough, in which case the dough is proofed in a closed container until the volume of the dough fills and seals the container. Alternatively, the dough may be packaged in flexible packaging after it has been proofed, in which case a sealing means is applied to the package in which the dough has been packed to render the package airtight. For purposes of this disclosure, the expression "containing means" will hereinafter be used to refer to both rigid containers and flexible packaging.
Depending on the product, storage temperature and the like, the minimum acceptable shelf life of commercially produced refrigerated doughs can be as long as about 90 days. At refrigeration temperatures, conventional yeast continue to produce carbon dioxide, causing the dough to continue rising and the dough ingredients to continue reacting, even after the dough has been packaged in a sealed containing means for storage. Because conventional yeast continue to produce carbon dioxide at refrigeration temperatures, overfermentation of the dough occurs, resulting in adverse changes in the dough theology. These changes negatively affect the taste, aroma, texture and other organoleptic qualities of the baked or cooked product prepared from the dough.
If the dough is packaged in a sealed containing means for storage at refrigeration temperatures, the continued carbon dioxide production by conventional yeast causes a continuous increase in the pressure within the containing means. Ultimately, the pressure inside the containing means increases to a point where the containing means raptures. This rupture can occur with conventional yeast in a matter of a week or less, which is well below the minimum acceptable shelf life for most commercially produced refrigeratable doughs.
For these reasons, refrigerated dough manufacturers generally have been unable to use yeast as the leavening agent in refrigerated doughs. Dough manufacturers rely instead on less preferred chemical leavening agents which comprise a combination of a leavening acid and a leavening base that react with one another to generate carbon dioxide. Chemical leavening permits control of the leavening process through controlling the quantity of reactants and the resulting volume of carbon dioxide. Use of chemical leavening agents usually eliminates the problems associated with conventional yeast such as overfermentation and container rupture by buildup of internal pressure, but the organoleptic qualities such as taste, aroma and texture of baked goods made from chemically leavened doughs are notably inferior to those of a yeast-leavened dough product. To improve the taste and aroma of chemically leavened dough products, yeast flavoring, such as inactive pasteurized yeast culture, may be added to chemically leavened dough. The flavor and texture of the products resulting from these doughs, however, remain inferior to yeast-leavened dough products.
Thus, there has been a long-felt but unsatisfied need in the field of refrigerated dough products to provide a refrigeratable yeast-leavened dough. It would be advantageous to provide a yeast-leavened dough which can be stored at refrigeration temperatures for extended periods of time without significantly adversely affecting the quality of the dough. It would also be desirable to provide a dough product, i.e. a dough in a sealed container, which is capable of being stored at refrigeration temperatures for extended periods of time without failure of the containing means.